A GPS device on an aeroplane is used to determine the distance between an aeroplane and the surface of the airport runway. However, the device can only work when it is within 1 km of the surface. The surface of the runway is described by the equation, 4x+3y+z=10 If the position of the aeroplane is (3,5,6) in units of km, determine whether the aeroplane is within range of the surface for the GPS device to work